Non-elastomeric piston load ring seal

Abstract

A safety valve piston seal assembly for safety valve pistons to improve the reliable of safety valve operation. The safety valve piston seal assembly is positioned about a safety valve piston and comprises components which divert a load path to the safety valve piston rather than to susceptible components of the seal assembly. The seal assembly may comprise a metal spring energized seal, an MSE backup ring adjacent the MSE seal and a load transfer assembly. The load assembly comprises a load ring, C-rings and a retaining sleeve. The retaining sleeve holds the two load rings and C-ring in place. The retaining sleeve restricts movement of the load ring.

Description

NON-ELASTOMERIC PISTON LOAD RING SEALCROSS-REFERENCE TO RELATED APPLICATION

[0001] The present document is based on and claims priority to U.S. Provisional Application Serial No. 62 / 570,578, filed March 27, 2024, which is incorporated herein by reference in its entirety.BACKGROUND

[0002] In many hydrocarbon well applications, various types of tubing strings may be deployed downhole in a borehole. For example, tubing strings may comprise completion equipment deployed in a wellbore to facilitate production of hydrocarbon fluids, e.g. oil and / or gas. The tubing string may include a safety valve which is actuated to restrict flow up through the tubing string upon the occurrence of various conditions. The safety valve often is actuated to a desired operational position via a piston which is shifted via hydraulic fluid supplied under pressure. The piston is combined with at least one seal assembly having components arranged to establish a seal between the piston and a surrounding surface. However, the seal assembly can be exposed to pressures, e.g. back pressures, which can lead to seal extrusion and pressure leaks behind the seal assemblies.SUMMARY

[0003] In general, a methodology and system are provided which facilitate improved sealing with respect to safety valve pistons so as to improve reliable safety valve operation. According to an embodiment, a safety valve piston seal assembly ispositioned about a safety valve piston and comprises components which divert a load path to the safety valve piston rather than to susceptible components of the seal assembly.

[0004] A system to facilitate operation of a safety valve according to one or more embodiments of the present disclosure includes a safety valve piston, and a safety valve piston seal assembly disposed about the safety valve piston. In one or more embodiments of the present disclosure, the safety valve piston seal assembly includes a metal spring energized (MSE) seal, an MSE backup ring adjacent the MSE seal and a load transfer assembly for directing a load to the safety valve piston.

[0005] A system according to one or more embodiments of the present disclosure includes an actuator and a seal assembly disposed about the actuator. In one or more embodiments of the present disclosure, the seal assembly includes an MSE seal and a plurality of load rings. The at least one load ring of the plurality of load rings being configured to transfer the load to the actuator without loading the MSE seal.

[0006] A system according to one or more embodiments of the present disclosure includes a plurality primary spring energized seals and a plurality secondary spring energized seals that are identical. The plurality primary spring energized seals and the plurality secondary spring energized seals both have an MSE seal and an MSE backup rings adjacent the MSE seal. The plurality primary spring energized seals further may include two primary spring energized seals located on opposite distal ends of the seal assembly providing a dual pressure seal configuration. The plurality secondary spring energized seals further may include two secondary spring energized seals located on opposite ends of the seal assembly internally of the plurality primary spring energized seals. The plurality secondary spring energized seals are backup spring energized seals. The plurality of load transfer assemblies may include a load ring engaged with the actuator; C-rings; and a retaining sleeve. The load ring engages a groove the safety valve piston. The retainer sleeve holds the load rings and C-ring in place and restricts movement of the load ring. The actuator is a piston body. The sealing element is a non- elastomeric seal. The system as recited where the load transfer assembly may include aload ring engaged with the safety valve piston to transfer loading to the safety valve piston.

[0007] However, many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein, and:

[0009] Figure 1 is a schematic illustration of a tubing string comprising a safety valve deployed in a borehole, according to an embodiment of the disclosure;

[0010] Figure 2 is a cross-sectional illustration of an example of a safety valve piston seal assembly mounted about a safety valve piston, according to an embodiment of the disclosure;

[0011] Figure 3 is a cross-sectional illustration of the non-elastomeric piston load ring seal, according to an embodiment of the disclosure.DETAILED DESCRIPTION

[0012] In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. However, it will be understood by those of ordinary skill in the art that the system and / or methodology maybe practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

[0013] The present disclosure generally relates to a methodology and system which facilitate improved sealing with respect to safety valve pistons so as to improve reliable safety valve operation. Depending on the application, the safety valve piston may have various sizes and configurations and may be operatively coupled with various types of safety valves. Examples of safety valves include flapper valves, ball valves, and other suitable valve configurations which can be utilized as safety valves along a tubing string.

[0014] This invention relates to a redundant spring energized (SE) seal, to help with liquid and gas tight dynamic sealing of safety valve hydraulic pistons, without the utilization of elastomers. A dynamic piston is located in a hydraulic chamber, hydraulic pressure is applied to the hydraulic chamber and the pressure is converted to axial displacement by the dynamic piston. The dynamic piston consists of 4 seals, 2 in each direction (uphole and downhole). These seals are unidirectional seals and are intended to relive back pressure if any is present. Each seal is mechanically separated by a system of load rings which transfers the mechanical force from the SE to the piston body. In the event that one of the seals is damaged, there is a second redundant SE.

[0015] Referring generally to FIG. 1, a schematic illustration shows an example of a well system 30 having a tubing string 32 deployed in a borehole 34, e.g. a wellbore. The tubing string 32 may comprise a downhole completion 36 combined with a safety valve 38 which can be actuated to different operational positions via a safety valve piston 40. The safety valve 38 may be used with many types of downhole completions 36 and in various hydrocarbon production operations and other types of well related operations.

[0016] Referring to FIG. 2 is an illustration of a safety valve 38. The safety valve 38 has a housing 42. The housing 42 has an upper housing 44, intermediate housing 46 and a lower housing 48. A bore 50 is within the upper housing 44, the intermediate housing 46 and the lower housing 48. The upper housing 44 has a control line port 52located on an outer surface of the upper housing 44. The control line port 52 receives a hydraulic line or control line (not shown) from the surface that is used to operate safety valve 38 which will be described in greater detail below. The safety valve 38 operate on fail-safe basis, where the control line remains pressurized at all times and any leak or failure results in a loss of control line pressure that closes the safety valve 38 to render the well safe.

[0017] The upper housing 44 has a chamber 54. Within the chamber 54 is a piston 40. The piston 40 has a piston seal assembly 56 on the outer surface creating a seal between the piston 40 and an inner surface of the chamber 54. In the current embodiment, the piston 40 has two piston seal assembly 56 wherein the first piston seal assembly 56 is located in the upper section of the piston 40 and the second piston seal assembly 56 is located on the lower end of the piston 40. The control line port 52 is in fluid communication with the chamber 54. A flow tube 58 resides in the bore 50 adjacent the intermediate housing 46. The flow tube 58 is configured to move telescopically within the bore 50 of the housing 42. As the flow tube 58 moves telescopically within the bore 50 of the housing 42, the flow tube 58 is adapted to shift a valve closure member 60 of the safety valve 38 between a closed position and an open position. In one or more embodiments of the present disclosure, the valve closure member 60 may be a flapper, as shown in FIG. 2. However, the valve closure member 60 may include a ball valve, a circulation valve, or another type of barrier valve without departing from the scope of the present disclosure.

[0018] The piston 40 is coupled to the flow tube 58. The piston 40 may be slidably received in the chamber 54 for slidable movement in response to pressurized fluid received from the control line port 52. The pressurized fluid applied against the piston 42 causes the flow tube 42 to move in a first direction. The safety valve 38 further comprises a spring located within the intermediate valve housing 46 of overall housing 42. The spring may comprise a coil spring. The spring is positioned around the flow tube 58. The spring resists motion in the first direction by exerting a force opposite the firstdirection. The lower losing 58 has a nose seal assembly 62 mounted below the valve closure member 60.

[0019] Referring generally to FIG. 3, the piston 40 is illustrated as combined with the piston seal assembly 56 which is disposed about the safety valve piston 40 on the inner diameter of the upper housing 44. In this embodiment, the safety valve piston seal assembly 52 comprises primary spring energized seals 64 and secondary spring energized seals 66. The primary spring energized seals 64 and secondary’ spring energized seals 66 are identical. The primary’ spring energized seals 64 and secondary' spring energized seals 66 have a metal spring energized (MSE) seal 70 and an MSE backup ring 72 disposed adjacent the MSE seal 70. The (MSE) seal 70 and the MSE backup ring 72 are unidirectional seals and are intended to relive pressure in one direction. The primary spring energized seals 64 and secondary spring energized seals 66 also has a hat ring 74.

[0020] Additionally, the piston seal assembly 56 comprises a load transfer assembly disposed between the primary spring energized seals 64 and secondary’ spring energized seals 66. According to an embodiment, the load transfer assembly 82 comprises a load ring 74, two C-rings 76 and a retaining sleeve 78. In FIG. 3, the C-ring 76 is disposed between load rings 74. Additionally, the C-ring 74 engages a groove in the piston 40. The retaining sleeve 78 overlaps two load rings 74 and the C-ring 76. The retaining sleeve 78 holds the two load rings and C-ring 74 in place. The retaining sleeve 78 restricts movement of the load ring 74.

[0021] As further illustrated in FIG. 3, the piston seal assembly 56 may comprise a plurality of primary' spring energized seals 64, a plurality of secondary’ spring energized seals 66 and a plurality of load transfer assemblies 82. The primary spring energized seals 64 are located at the distal ends of the piston seal assembly 56. Each of the primary spring energized seals 64 are located at the opposite ends of the piston seal assembly 56. Adjacent to the primary spring energized seals 64 is the load transfer assembly 82 and adjacent to the load transfer assembly 82 is the secondary spring energized seals 66. The load transfer assembly 82 may be between the primary’ spring energized seal 62 and thesecondary spring energized seal 64 Additionally the load transfer assembly 82 may be located between two secondary' spring energized seals 64. As illustrated in FIG. 3, there are two primary' spring energized seal 62, two secondary spring energized seal 64 and three load transfer assemblies 82. The number of primary spring energized seals, secondary spring energized seals and load transfer assemblies 82 may be adjusted without departing from the scope of the present disclosure.

[0022] The primary spring energized seals 64 and secondary spring energized seals 66 that are on opposite sides of the piston seal assembly 56 are arranged in opposite directions. In this configuration, the piston seal assembly 56 provides a dual pressure seal configuration. This protects against pressure from both directions by providing load paths routed to the piston 40. When pressure is applied to the MSE seal 44, the MSE seal 44 loads on the MSE backup ring 46 which, in turn, transfers the load to the load transfer assembly 82. The load transfer assembly 82 includes the load ring 74 engaged with the safety valve piston 40 to transfer loading to the safety valve piston.

[0023] While one or more embodiments of the present disclosure generally relates to a methodology and system to facilitate improved sealing with respect to safety valve pistons so as to improve reliable safety valve operation, the methodology and system according to one or more embodiments of the present disclosure may also be applied to any downhole hydraulically operating completions equipment, such as flow control valves and formation isolation valves, for example. In such other embodiments, the system may more generally include a piston or other type of actuator, which may be hydraulically powered, and a sealing assembly, which may include various components and seals of different shapes and configurations that are either elastomeric or non- elastomeric.

[0024] Although a few embodiments of the disclosure have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of thisdisclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.

Claims

CLAIMSWhat is claimed is:

1. A system to facilitate operation of a safety valve, comprising: a piston; and a piston seal assembly disposed about the piston, the piston seal assembly comprising: a metal spring energized (MSE) seal; an MSE backup ring adjacent the MSE seal; and a load transfer assembly for directing a load to the safety valve piston.

2. The system as recited in claim 1, wherein the load transfer assembly comprises a load ring engaged with the safety valve piston to transfer loading to the safety valve piston.

3. The system as recited in claim 2, wherein the load ring engages a groove the safety valve piston.

4. The system as recited in claim 3, wherein the load transfer assembly further comprises C-rings and a retaining sleeve.

5. The system as recited in claim 4, wherein the retainer sleeve holds the load rings and C-ring in place and restricts movement of the load ring.

6. The system as recited in claim 1, wherein the safety valve piston seal assembly further comprises a hat ring disposed adjacent the MSE seal.

7. The system as recited in claim 1, wherein the safety valve piston seal assembly comprises a plurality of safety valve piston seal assemblies arranged to provide a dual pressure seal configuration.

8. The system of claim 1, wherein the safety valve piston seal assembly disposed about the piston further comprises a first piston seal assembly located at one end of the piston and a second piston seal assembly located at the opposite end of the piston.

9. The system of claim 1, wherein the metal spring energized seal and MSE backup ring adjacent the MSE seal are located on both ends of the piston.

10. A system comprising: an actuator; and a seal assembly disposed about the actuator, the seal assembly comprising: a plurality primary spring energized seals; a plurality secondary spring energized seals; and a plurality of load transfer assemblies for directing a load to the safety valve piston.

11. The system of claim 8, wherein the plurality primary spring energized seals and the plurality secondary spring energized seals are identical and comprises: a metal spring energized (MSE) seal; and an MSE backup ring adjacent the MSE seal.

12. The system of claim 8, wherein the plurality primary spring energized seals further comprises two primary spring energized seals located on opposite distal ends of the seal assembly providing a dual pressure seal configuration.

13. The system of claim 10, wherein the plurality secondary spring energized seals further comprises two secondary spring energized seals located on opposite ends of the seal assembly internally of the plurality primary spring energized seals.

14. The system of claim 8, wherein the plurality secondary spring energi zed seals are backup spring energized seals.

15. The system of claim 8, wherein the plurality of load transfer assemblies further comprises: a load ring engaged with the actuator;C-rings; and a retaining sleeve.

16. The system as recited in claim 13, wherein the load ring engages a groove the safety valve piston.

17. The system as recited in claim 14, wherein the retainer sleeve holds the load rings and C-ring in place and restricts movement of the load ring.

18. The system of claim 8, wherein the seal assembly disposed about the actuator further comprises a first piston seal assembly located at one end of the actuator and a second piston seal assembly located at the opposite end of the actuator.

19. The system of claim 8, wherein the actuator is a piston body.

20. The system of claim 8, wherein the sealing element is a non-elastomeric seal.

Images